Reverse flow air filter arrangement and method

ABSTRACT

A reverse flow air filter arrangement is provided. The arrangement includes a filter element having first and second end caps, the second end cap having a central drainage aperture. A funnel shape on an interior surface of second end cap is used to direct moisture flow to the drainage aperture. The arrangement includes a housing in which the filter element is positioned, operatively, during use. Certain features in the housing facilitate moisture withdrawal from the filter element while also inhibiting interference with sealing between the filter element and the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part application of U.S.Ser. No. 08/742,244, filed Oct. 31, 1996, now U.S. Pat. No. 5,690,712.U.S. Ser. No. 08/742,244 was a divisional of U.S. Ser. No. 08/344,371,filed Nov. 23, 1994, now U.S. Pat. No. 5,613,992. The completedisclosure of application U.S. Ser. No. 08/742,244 is incorporatedherein by reference. Application Ser. No. 08/344,371 issued on Mar. 25,1997 as U.S. Pat. No. 5,613,992. The complete disclosures of U.S. Pat.No. 5,613,992 and the application which issued as the '992 patent arealso incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to reverse flow air cleaner arrangements.That is, the invention concerns air cleaner arrangements whereinfiltering flow is in a direction with the "clean" side of the air filterbeing around an exterior thereof, and the "dirty" side of the air filterbeing along an interior thereof. The invention particularly concernssuch air cleaner arrangements having drainage systems for wateraccumulating in an interior of associated air filter elements. Theinvention also concerns provision of preferred components, such as airfilter elements, for use with such arrangements; and, to methodsinvolving the use of such arrangements.

BACKGROUND OF THE INVENTION

In general, air cleaner arrangements include a housing and an air filterelement. The housing is configured such that air is directed through theair filter element, for filtering. Various geometric configurations ofthe air cleaner housing, the air filter element, and related sealarrangements are used to effect this.

Many air cleaner arrangements include generally cylindrical air filterelements. Such elements typically include filter media arranged in acylindrical pattern, with end caps. Seal arrangements are used either onor in conjunction with the end caps, to provide appropriate sealing withthe housing or other portions of the air cleaner, and to control thedirection of air flow.

Reverse air flow air cleaner arrangements are generally those in whichair is directed to an interior of the air filter element before it isfiltered, and the air is filtered as it passes through the air filterelement from the interior to the exterior. If the air filter element iscylindrical, this means that the unfiltered air is directed into theinterior of the cylinder, and then through the filter media, to anexterior, during filtering. Material entrained in the air directed intothe air filter, then, is left along an interior of the cylindricalfilter media.

Consider, for example, a reverse flow air cleaner arrangement, having acylindrical air filter element, utilized on an over the highway truck.Air directed into the interior of the cylindrical element may includedust, leaves, large particulates, and even moisture entrained therein.This material will tend to build up in the interior of the air filterelement, in time. If the water depth inside the air filter becomessignificant, the water, alone or with fine particulates or salt insuspension, can permeate the filter media. This has the potential todamage engine components. It would be preferred that arrangements beprovided to drain the water from the interior of the filter element.

In those arrangements wherein the filter element is operationallyoriented such that the longitudinal axis of the cylindrical air filteris substantially vertical, drainage arrangements involving drainageapertures in one of the end caps have been used. In general, these haveinvolved offset (from a central location) apertures in one end cap, andunless the air filter element is oriented nearly perfectly vertically,drainage is inefficient. Also, in such arrangements debris can sometimescollect along interior surfaces of the housing when the arrangement isopened and the element is removed; and, unless the housing is thoroughlycleaned before the element is reinserted into the housing, the debriscan interfere with attainment of a good seal at critical locations.

Summary of the Disclosure of U.S. Ser. No. 08/742,244

According to the disclosure of U.S. Ser. No. 08/742,244, an air filterarrangement is provided. The air filter arrangement includes a housingand an air filter element having first and second opposite end caps,filter media and an open filter interior. The first end cap has an airinlet opening therein, for air to be passed into the arrangement to befiltered. The second end cap has a central drainage aperture and aninterior surface constructed and arranged to funnel moisture thatcollects on the second end cap interior surface to the central drainageaperture, and outwardly from the filter element. The central drainageaperture is preferably positioned at a center of the second end cap,with a longitudinal axis of the air filter element passing therethrough.The air filter arrangement also includes an air flow directionarrangement constructed and arranged to direct air flow into thehousing, into the open filter interior, through the filter media forfiltering and then outwardly from the housing, as filtered air. The airflow direction arrangement generally comprises various features of thehousing, seals and filter element.

Preferably, the interior surface of the second end cap is circular. Incertain embodiments it includes a plurality of radially directed troughswhich terminate in the central drainage aperture. The troughs can beused to help funnel and direct moisture collected on an interior surfaceof the air filter element in use (i.e., "when operationally" or"operatively" assembled).

In certain preferred arrangements, according to the U.S. Ser. No.08/742,244 disclosure, the second end cap includes an outer annularcompressible portion and the housing includes an annular sealing surfaceagainst which the second end cap outer annular compressible portion issealed, when the air filter arrangement is operatively assembled foruse. Such a seal is referred to herein as a peripheral or annular radialseal, around the second end cap. That is, in this context the term"annular" refers to a sealing portion around the outside of the end cap,which seals under radial compression.

In a preferred embodiment, according to the U.S. Ser. No. 08/742,244disclosure, the housing includes a base having a central, preferablyrecessed, pan and a sealing bead circumferentially positioned around thecentral recessed pan. A drainage aperture is provided in the centralpan, so that water collected in the pan can be removed from the housing.With such an arrangement, preferably the second end cap is constructedand arranged to form a secondary seal with the sealing bead in the base,when the air filter element is operatively positioned within thehousing. Preferably the manner of engagement with the seal bead is byprovision of a mating "trough" in the second end cap outer surface.

According to the U.S. Ser. No. 08/742,244 disclosure, preferably thesecond end cap outer surface has an outer edge or lip; and, the secondend cap outer surface is recessed (or depressed) in extension betweenthe outer edge and the trough which engages the sealing bead and thebase. In this manner, a preferred gap or space is provided between thefilter element second end cap, and the housing base, in the regionbetween the sealing bead of the base and an outer peripheral area of thebase. A space in this location accommodates debris that may collect inthe housing, without interference with the seal between the second endcap and the housing. This is facilitated by those arrangements involvingprovision of the seal along an annular portion of the end cap, as aradial seal, rather than as an end or axial seal.

According to the U.S. Ser. No. 08/742,244 disclosure, preferably thesecond end cap outer surface is configured to provide a funnel surfacehaving a declination angle of at least about 1°, and preferably 1° to3°, in the region of extension between the outer edge of the second endcap and the portion of the end cap which engages the seal bead in thebase.

In preferred arrangements, according to the U.S. Ser. No. 08/742,244disclosure, an evacuation valve is mounted in the drainage aperture ofthe recessed pan in the base. This provides for a preferred, controlled,drainage of moisture from the system.

In preferred embodiments, according to the U.S. Ser. No. 08/742,244disclosure, a soft polymeric material is utilized for the first andsecond end caps. Preferably each of the polymeric end caps comprisepolyurethane. For the end caps, a polyurethane foam material having an"as molded" density of about 14-22 lbs per ft³ will be preferred (mostpreferably about 18.4). In some embodiments, the same material can beutilized for both end caps.

In preferred constructions, according to the U.S. Ser. No. 08/742,244disclosure, an air inlet tube is provided in the housing, which isconfigured to generate a radial seal with the first end cap of thefilter element.

In an alternate embodiment, described in the U.S. Ser. No. 08/742,244disclosure, an arrangement having a sheet metal end cap as the secondend cap is provided. This arrangement is preferably axially sealed, byprovision of a primary seal gasket axially compressed between the secondend cap and the base, when the air filter arrangement is operationallyassembled. A secondary gasket can also be provided in such arrangementsbetween a selected portion of the second end cap and the housing base.

According to the U.S. Ser. No. 08/742,244 disclosure, a preferred filterelement is provided. The preferred filter element comprises a generallycylindrical extension of filter media. The filter media may be, forexample, a pleated paper filter media. Preferably, an inner supportliner and an outer support liner are provided, for the cylindricalextension of filter media. Preferably the arrangement has first andsecond end caps, the first end cap including an air inlet openingtherein. The second end cap preferably has a central drainage apertureand an interior surface constructed and arranged to funnel moisture,collected on the interior surface of the second end cap, to the centraldrainage aperture. The central drainage aperture is preferably locatedat an approximate center of the end cap, on a longitudinal axis of thecylindrical extension of filter media. A preferred configuration for theinterior surface of the second end cap, is as an interior of a funnel.In some embodiments, the second end cap interior surface includes aplurality of radially directed troughs therein, which terminate at thecentral drainage aperture.

Other preferred features for the preferred air filter element describedin the U.S. Ser. No. 08/742,244 disclosure include: a circular sealingtrough on an outer surface of the second end cap; and, a recess betweenan outer edge of the end cap outer surface and the circular trough.Also, a compressible region providing for a radial seal along an annularportion of the second end cap is preferred.

According to the U.S. Ser. No. 08/742,244 disclosure, a method ofoperating a reverse flow air filter arrangement is provided. In general,the method comprises collecting moisture within the filter element anddraining the moisture from the filter element through a central aperturein the end cap, by funneling the moisture to the central aperture.

SUMMARY OF THE PRESENT DISCLOSURE

According to the portion of the present specification which comprisesadded disclosure relating to FIGS. 9-14, the end cap which includes thedrainage aperture therein, is provided in a preferred compositestructure. The composite results from an outer portion comprising asoft, compressible, polymeric material; and, an inner "pre-form" orinsert, which becomes positioned between the polymeric material and theinner liner, during molding. The insert has preferred inner surfacecharacteristics, to accomplish desirable flow of liquid to the drainageaperture, and outwardly from an interior of the filter element. Inaddition, it has preferred features to facilitate molding using a freerise technique.

The preferred "pre-form" or insert also has depending legs withoutwardly projecting feet. The legs and feet operate, cooperatively, asa mold stand-off for media. An underside of each foot has a beadthereon, to facilitate this.

Further features and advantages from the preferred inserts and"pre-forms" described herein, as well as techniques for use, will beapparent from the more detailed description below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of an air cleaner arrangementaccording to the present invention.

FIG. 2 is a top plan view of the arrangement shown in FIG. 1.

FIG. 3 is an exploded plan view of the arrangement shown in FIG. 1.

FIG. 4 is an enlarged fragmentary side cross-sectional view of a portionof the arrangement shown in FIG. 1; FIG. 4 being generally taken alongline 4--4, FIG. 1.

FIG. 5 is a fragmentary cross-sectional view of a portion of thearrangement shown in FIG. 1; FIG. 5 generally being taken along line5--5, FIG. 1.

FIG. 6 is a fragmentary exploded view of a portion of the arrangementshown in FIG. 5.

FIG. 7 is a fragmentary top plan view of a portion of the arrangementshown in FIG. 6.

FIG. 8 is a fragmentary cross-sectional view of an alternate embodimentto that shown in FIGS. 1-7.

FIG. 9 is a fragmentary cross-sectional view of a second alternateembodiment of the present invention, taken from a point of viewanalogous to that used for FIG. 5.

FIG. 10 is a top plan view of a component used in the alternateembodiment of FIG. 9.

FIG. 11 is a cross-sectional view of the component depicted in FIG. 10,taken along line 11--11 thereof.

FIG. 12 is a schematic representation of a method of assembling theembodiment of FIG. 9.

FIG. 13 is a fragmentary schematic representation of a cross-section ofa mold configuration usable to generate the assembly of FIG. 9.

FIG. 14 is a bottom plan view of a filter element including thecomponent of FIGS. 10 and 11 therein.

FIG. 15 is a schematic cross-sectional view depicting the component ofFIG. 10 positioned in the mold of FIG. 13.

FIG. 16 is an enlarged view of one of the legs of the component depictedin FIG. 11.

DETAILED DESCRIPTION

Disclosure of U.S. Ser. No. 08/742,244 and Its Parent U.S. Ser. No.08/344,371

The reference numeral 1, FIG. 1, generally designates an air cleanerassembly according to the disclosure of Ser. No. 08/742,244. FIG. 1 is aside elevational view of air cleaner assembly 1. In the Figure, housing2 is depicted generally. The housing 2 includes an inlet construction 3and a filter element receiver or can 4. Can 4 includes outlet 7. In use,air to be filtered passes through inlet construction 3, and is directedto an interior of can 4. Within can 4, the air is directed through afilter element, not viewable in FIG. 1. After being filtered by thefilter element, the air passes outwardly through outlet 7 and isdirected to the air intake of the engine, not shown. Herein, the term"air flow direction arrangement" is used to generally refer to thosefeatures of an air filter arrangement which direct air flow in thepreferred manner or along a preferred path. The term may refer to avariety of features, and typically refers to internal configurations ofthe housing and filter element, as well as the various seals.

Still referring to FIG. 1, inlet construction 3 is mounted on can 4, andis secured thereto by bolts 8 and nuts 9. Access to the interior of can4, and a filter element positioned therein, is obtained by looseningbolts 8 and separating inlet construction 3 from can 4.

For the particular construction shown, inlet construction 3 includes anupper dome 12, perforated air inlet screen 13 and an inlet tube 14 (theinlet tube not being viewable in FIG. 1, but being shown in FIG. 4 incross-section).

Still referring to FIG. 1, can 4 includes a drainage aperture therein,the drainage aperture not being viewable in FIG. 1, but being shown atreference numeral 18 in FIG. 5. The drainage aperture is covered by anevacuation valve 19. The evacuation valve 19 may be, for example, asdescribed in U.S. Pat. No. 3,429,108, the disclosure of which isincorporated herein by reference. In general, the drainage aperture 18is positioned in a portion of can 4 which will be, when assembly 1 isoperatively installed, positioned at the bottom of the assembly 1. Thus,water will tend to collect near aperture 18, and be drained therefrom,in use. This will be more readily apparent from further descriptionswherein internal details of air cleaner assembly 1 are presented.

Referring to FIG. 2, air cleaner assembly 1 includes four bolts and nuts9 for securing the inlet construction 3 to the filter can 4. While thenumber of bolts used may be varied, depending on the particularapplication, it is an advantage of constructions according to the08/742,244 disclosure that filter assemblies as large as about 15 inchesin outside diameter can be reliably secured closed, with as few as aboutthree to five bolts. Features which facilitate this, will be apparentfrom further descriptions.

An exploded view of air cleaner assembly 1 is depicted in FIG. 3. InFIG. 3, air cleaner assembly 1 is shown with inlet construction 3separated from filter can 4, and with air cleaner element 21 removedfrom can 4. For the particular arrangement shown, air cleaner element 21is generally cylindrical. Element 21 includes first and second end caps23 and 24; filter media 25; inner support 26 (FIG. 4); and, outersupport 27. For the particular embodiment shown, filter media 25comprises a pleated paper construction 30. In general, pleated paperconstruction 30 comprises a cylinder 31 of fluted paper with the flutesrunning in a direction longitudinally along, and generally parallel to,a central axis 33 of the element 21. It will be understood thatalternate filter media constructions could be utilized. In general, thefilter media 25 extends between the end caps 23 and 24. For assembly 1depicted, end caps 23 and 24 comprise polymeric material as describedbelow, in which opposite ends of the filter media 25 are set or potted.

In FIG. 4 a fragmentary cross-sectional view of air cleaner assembly 1is depicted. In FIG. 4, the inlet construction 3 and portions of aircleaner assembly 1, in association therewith, are depicted.

In general, the filter media 25 is positioned between inner support 26and outer support 27. Each support generally comprises a tubular orcylindrical extension of perforated metal or expanded metal, oppositeends of which are also set in, or potted in, end caps 23 and 24.

In general, end cap 23 is open and end cap 24 is closed. That is, endcap 23 includes a large inlet aperture 28 (FIG. 4) therein, forintroduction of air to be filtered into filter element interior 35. Endcap 24, on the other hand, is generally closed, but for a drainageaperture extending therethrough as described below.

Still referring to FIG. 4, it can be seen that inlet construction 3includes inlet tube 14. When assembled, inlet tube 14 extends intoaperture 28 in end cap 23. At least in this location, end cap 23 ispreferably formed of a soft compressible material. When inlet tube 14 isnot inserted into aperture 28, at least a portion of aperture 28 in itsuncompressed state will generally have an inside diameter slightlylarger than an outside diameter of section 39 of inlet tube 14; i.e.,the portion of tube 14 which engages end cap 23 when arrangement 1 isoperatively assembled. Thus, when inlet tube 14 is inserted throughaperture 28, end cap material in region 40 will be compressed. In thismanner a seal is formed at region 41. Such seals are described, forexample, in conjunction with air cleaner assemblies in U.S. Pat. No. B24,720,292, the disclosure of which are incorporated herein by reference.It is noted that the arrangement of U.S. Pat. No. 4,720,282 is notnecessarily a reverse flow arrangement; however, the principles relatingto the formation of the seal are basically the same. Such seals aresometimes referred to as "radial" or "radial-type" seals, since theforces maintaining sealing are directed radially around a centrallongitudinal axis 33 (FIG. 3) of the tube and element, rather thanco-extensively or coaxially therewith. For the particular arrangementshown in FIGS. 1-7, material at region 40 is compressed between andagainst both inlet tube 14 and inner support 26; that is, inner support26 is set sufficiently deeply into end cap 23 that a portion of it ispositioned behind compressible region 40, to provide support. Thus, agood seal is effected. The shape of aperture 28 in region 41 willpreferably be as a ribbed or stepped funnel (or tapered), to facilitateengagement. Such a ribbed arrangement is shown in 5,238,474,incorporated herein by reference. In U.S. Pat. No. 4,720,292 a similarlytapered surface without ribs is shown. Preferably, three equally sizedsteps from a region of diameter about the same as the inlet tube O.D.are used, with the amount of total compression of the smallest diameterrib (i.e., region of most compression) being about 21.4% (20% ±3%). Thesize of each step will depend in part on the diameter of the inlet tube.In general, for an element used with an inlet tube having an O.D. of175-200 mm, a total compression thereacross of 2.7 mm (or 1.35 mm forany location since any location compresses about one-half of the totalcompression) for the smallest rib would be used.

It will be understood, then, that for the arrangement shown in FIGS.1-7, seal 41 prevents air directed into filter interior 35 through inlettube 14 from bypassing filter media 25 and getting into clean air plenum44. In general, the various portions of the arrangement 4 cooperate asan air flow direction arrangement to direct air flow: into the housing,into the filter interior, through the filter media and outwardly fromthe housing.

Another point of potential leakage of unfiltered air into clean airplenum 44 is presented by the location whereat inlet construction 3engages filter can 4. This region is located generally at 50; i.e.,where bolts 8 secure inlet construction 3 to filter can 4. At region 50,inlet construction 3 is provided with an outwardly extending flange 52;and, can 4 is provided with an outwardly extending flange 53. Seal ring54 is provided in extension around can 4, between flanges 52 and 53.Seal ring 54 is positioned at a location between bolts 8 and filterelement 21. When bolts 8 are tightened, seal ring 54 will be compressedbetween flanges 52 and 53, i.e., at a location between inletconstruction 3 and filter can 4, providing a seal. Thus, air leakageinto plenum 44, by passage between portions of can 4 and inletconstruction 3 is inhibited. Filter ring 54 may be a conventional O-ringtype gasket.

Attention is now directed to FIG. 5, which is a cross-sectional viewshowing the "bottom half" or "opposite end" of assembly 1 from the endwhereat inlet construction 3 is located. Referring to FIG. 5, referencenumeral 60 generally designates an end of can wall 61. Within end 60 ispositioned a cover or base 63 of can 4. Base 63 is configured in apreferred manner, to advantage.

For the particular embodiment shown, base 63 is circular, to conform tothe cross-sectional configuration of can wall 61 at end 60. For theparticular embodiment shown, base 63 is also radially symmetric. Thatis, the features of base 63 are configured radially symmetrically aboutcentral axis 33. Base 63 includes end flange 65 for engagement with end60, for example by means of welds.

Progressing inwardly from flange 65 toward its center 66, the featuresof the preferred base 63 depicted are as follows: an annularcircumferential sealing surface 67 is provided; a bend or corner 68; anend surface 69; a secondary seal bead or ridge 70; and, a central pan71. In the center 66 of pan 71, drainage aperture 18 is provided.

The arrangement shown in FIGS. 1-7 is configured preferentially so thatwhen oriented for use, pan 71 is at a lowermost or recessed location, sothat water will drain to pan 71 under gravity influence. As the waterdrains into pan 71, it will be drained outwardly from air cleanerassembly 1 through drainage aperture 18. Particular features describedherein are provided, for a preferred manner of debris collection withinassembly 1 and drainage of collected moisture to aperture 18.

Still referring to FIG. 5, filter element 21 includes end cap 24thereon. End cap 24 is of an appropriate material, and of appropriatesize, so that when it is pushed into and against base 63, an outercircumferential surface 75 of the end cap 24 engages surface 67 of base63 in a sealing manner. That is, an annular seal 76 is formed in region77, circumferentially around end cap 24. This is facilitated bypreferably providing surface 67 in a cylindrical configuration extendinggenerally parallel to axis 33. The seal prevents unfiltered air fromreaching clean air plenum 44. As a result of the circumferential seal,sealing against flow of air is not required between any other portionsof filter element 21 and base 63. A secondary seal 80, described hereinbelow, is provided, however, between end cap 24 and base 63. Thesecondary seal 80 is generally provided to inhibit movement of debris orwater into region 81, between element 21 and base 63, rather than tonecessarily prevent flow of air therebetween. Thus, while seal 76 shouldbe in a form sufficient to withstand a pressure differential thereacrossof up to about 40 inches of H₂ O, secondary seal 80 will generally besufficient if it can maintain at pressure differential thereacross of upto about 2 inches (and typically only up to about 2-4 inches) of H₂ O.

Still referring to FIG. 5, end cap 24 includes a circular recess ortrough 85 therein. Trough 85 is sized and configured to receive andsealingly engage bead 70. Trough 85 should be sized, relative to bead70, such that when element 21 is pressed against base 63, bead 70 ispushed into trough 85 to form a seal therewith, capable of holding apressure differential of up to about 2-4 inches of H₂ O. This could bereadily accomplished by forming the related region 86 of end cap 24 ofan appropriately soft compressible polymeric material into which rigidbead 70 can be pressed, for engagement.

Referring to FIGS. 5 and 6, it is noted that for the preferredembodiment depicted surface 90 of end cap 24 is recessed from outer edge91 to region 92, so that a space between surface 90 and end surface 69is provided, when filter element 21 is operatively positioned within can4. The amount of recess can be varied, depending upon the size of thearrangement. In general, an angle of inclination from edge 91 to region92 on the order of about 1° to 3° will be sufficient.

Advantages which result from this inclination, will be apparent fromfurther descriptions herein below. In general, the space between surface90 and end surface 69 ensures that there will not be interference witheasy formation of the annular, radial, seal.

Still referring to FIGS. 5 and 6, internal surface 94 of end cap 24 isconfigured to slope downwardly, when the assembly 1 is oriented as shownin FIGS. 5 and 6, in extension from outer region 95 toward centralaperture 96. Preferably, internal surface 95 is conical or funnel shapedin this region. Thus, any water which collects on internal surface 94will tend to flow toward central aperture 96 and therethrough, intorecessed pan 71. In some embodiments, recessed radial troughs extendingoutwardly and upwardly from central aperture 96 can be used tofacilitate this flow. Such an arrangement is shown, for example, in FIG.7 (a top plan view of element 21) wherein four evenly (radially) spaced,recessed, troughs 99 are depicted. It will be understood that each oftroughs 99 generally inclines downwardly as it extends from region 95toward central aperture 96, to facilitate collection of water withininterior 35 and direction of the collected water to central aperture 96.An advantage to troughs 99 is that should a leaf or other largeparticulate material become positioned over central aperture 96, watercan still flow into and through the aperture 96 by means of the troughs99, since the troughs 99 can generally direct water flow underneathdebris collected on top of internal surface 94.

Numerous advantages result from the preferred features described. Asassembly 1 is used for a filtering operation, air will generally flowthrough inlet tube 14 into interior 35, carrying within it moistureand/or debris. The moisture and debris will tend to collect withininterior 35, on internal surface 94 of end cap 24, since arrangement 1will generally be configured with end cap 24 positioned beneath inlettube 14. Water collecting on internal surface 95 will generally bedirected toward central aperture 96, for drainage into recessed pan 71and eventually drainage outwardly from assembly 1 through drainageaperture 18. Evacuation valve 19, if used, will facilitate this.

Because sealing between end cap 24 and housing 2 is positioned alongannular circular sealing surface 67, i.e., at region 77, the criticalsealing is not located at a surface where debris is likely to be spreador collect, as element 21 is removed from and replaced into housing 2,during typical maintenance operations.

Because surface 90 is recessed from end surface 69, in extension betweenedge 91 and region 92, any debris which may spread along end surface 69during operations involving removal and insertion of filter elementsinto housing 2, will not likely interfere with sufficient insertion ofthe element 21 into can 4 for the development of a good seal at region77. That is, some debris buildup along the bottom of base 63 is welltolerated.

Also, secondary seal 80 will inhibit the likelihood of debris ormoisture moving from pan 71 into surface 69, or region 77. This willalso help facilitate removal of moisture from assembly 1, since themoisture will tend to concentrate near drainage aperture 18.

In FIG. 6, the arrangement of FIG. 5 is shown exploded. From this, apreferred configuration for surface 75, relative to circular (annular)sealing surface 67 will be understood. In particular, surface 75includes steps 101, 102 and 103, with extensions 105 and 106therebetween. Step 103 is approximately the same diameter as circularsealing surface 67, and facilitates guidance of air cleaner element 21into engagement with base 63, during assembly. Step 102 is preferablyslightly larger in diameter than circular sealing surface 67, and step101 is preferably slightly larger in diameter than step 102, to enhancecompression of end cap material in region 77, as element 21 is insertedinto base 63, during assembly. In this manner, a good seal is formed. Ingeneral, for preferred embodiments the actual amount of compression ofthe end cap in region or step 102 is 3 mm±1 mm on diameter (or 1.5 mm atany location). The diameter of step 102 is preferably about 1.5 mmgreater than step 101, and about 3 mm greater than step 103. The amountof compression in step 102 would preferably be about 21.4% (20% ±3%).

As indicated, the arrangement described with respect to FIGS. 1-7generally utilizes a radial seal engagement in region 77. Alternatesealing arrangements may be utilized. An example of such an arrangementis illustrated in the alternate embodiment of FIG. 8.

In FIG. 8 an alternate application of principles according to the Ser.No. 08/742,244 disclosure is provided. FIG. 8 illustrates an engagementbetween an air cleaner assembly base and a filter element, to provideadvantages according to the present invention, in an arrangement whichutilizes an "axial seal" between the filter element and the housing, atleast at this location.

In general, an axial seal is a seal which is maintained by forcesdirected along an axis of the filter element, as opposed to radial sealarrangements described with respect to FIGS. 1-7 which use forcesdirected radially around an axis. Axial seal arrangements have beenwidely utilized in filter elements in a variety of manners. Often acentral yoke or axle is provided, along which forces are directedbetween the housing in the element. In other systems a bolt engagementbetween portions of the housing are used to compress the element againstone end or both ends of the housing. The O-ring 54 in the embodiment ofFIGS. 1-7, for example, provides sealing by axial compression.

FIG. 8 is a fragmentary cross-sectional view of an alternate air cleanerassembly 115. The air cleaner assembly 115 is also a reverse flowarrangement. Assembly 115 includes housing 116 and air filter element117. An inlet arrangement, not depicted, would be utilized to direct airflow into interior 118. Air flow would then be through filter element117 into clean air plenum 120, and outwardly through a conventionaloutlet, not shown, into an air intake for an engine.

In FIG. 8 the outer wall of the housing 116 or can, is generally shownat 121. The housing end or base 123 is configured to perform functionsgenerally analogous to those for base 63, FIGS. 1-7.

Still referring to FIG. 8, filter element 117 has a sheet metal end cap,such as end cap 125. The filter element 117 includes filter media 126potted within the end cap 125 (the opposite end cap not being shown inFIG. 8). Element 117 includes inner and outer liners 127 and 128respectively.

Sealing between element 117 and base 123, against air flow therebetween,is provided by gasket 130. That is, an appropriate mechanism to applyaxial forces in the direction of arrow 131 against element 117 should beprovided, to compress gasket 130 between end cap 125 and base 123 andform a seal. This can be accomplished with bolts used to drive an endcover or inlet construction against an opposite end of element 117.Preferably appropriate sizes and configurations of the element 117, base123 and gasket 130 are selected, so that the seal of gasket 130 will besufficient to hold a pressure differential at least about 40 inches ofH₂ O thereacross. In this manner, unfiltered air in region 132 isprevented from reaching clean air plenum 120, in use.

In general, the features of the preferred base 123 depicted are asfollows. Base 123 is radially symmetric and includes outer flange 135,for securement to can wall 121, such as by welding. Base or recess area136 is provided for a receipt of gasket 130 therein, during sealing.This is accommodated by recessed area 136 forming a trough 137. Region138, of base 123, is raised above trough 137, and provides a raisedsurface 139 for provision of a secondary seal, as described below. Base123 then defines pan 145, by downwardly extending or declining wall 146,towards a recessed central aperture 147.

With respect to the filter element, end cap 125 includes a downwardlyslanted surface 149 toward central pan 150 having drainage aperture 151therein.

A secondary seal between end cap 125 and surface 139 is provided bysecondary seal gasket 155. This gasket 155 is intended to inhibit themigration of moisture and debris from recessed pan 145 into region 137,whereat it could interfere with seal gasket 130. Secondary gasket 155need only provide a seal sufficient to inhibit substantial migration ofmoisture and debris, and does not need to be a primary air seal. Thus,gasket 155 need only be compressed sufficiently to withstand a pressuredifferential of up to about 2-4 inches of H₂ O thereacross.

Operation of assembly 115 will now be apparent. When assembled,sufficient axial pressure is applied along the direction of arrow 131,to provide an air seal end at gasket 130 and a secondary seal at gasket155. Debris and moisture directed into interior 118 will generallycollect in pan 150. In general, moisture collecting along recessedsurfaces 149 will be directed downwardly toward and through aperture151, into pan 145 of base 123, and eventually through drainage aperture147 and outwardly from assembly 115. It will be understood that a troughsystem (analogous to that described for FIGS. 1-7) may be utilized inpan 150, if desired, to inhibit the likelihood of drainage aperture 151becoming closed or plugged by debris.

Materials Described in Ser. No. 08/742,244

According to Ser. No. 08/742,244, while a wide variety of materials maybe utilized in the constructions, the principles described wereparticularly developed for use, to advantage, with systems constructedfrom certain preferred materials. In general, the constructions weredesigned for utilization with sheet metal housing systems, or stainlesssteel housing systems; i.e., arrangements wherein the housing, inparticular the inlet assembly, the can and the base, are formed fromsheet metal or stainless steel parts which are secured to one another asby welding. Materials useful for such fabrication include 0.075-0.025(incorrectly stated as 0.75-0.25 in the earlier disclosures) inchesthick stainless steel or sheet metal, although other thickness areuseable. Plastics can also be used.

For the arrangement of FIGS. 1-7, the preferred end cap materialdescribed in Ser. No. 08/742,244 for forming the regions in the end capthat need to be compressed to form a seal is a soft polymeric materialsuch as foamed polyurethane. Such materials include the followingpolyurethane, processed to an end product having an as molded density of14-22 pounds per cubic foot (lbs/ft³).

The preferred polyurethane described in Ser. No. 08/742,244 comprises amaterial made with I35453R resin and I3050U isocyanate. The materialsshould be mixed in a mix ratio of 100 parts I35453 resin to 36.2 partsI3050U isocyanate (by weight). The specific gravity of the resin is 1.04(8.7 lbs/gallon) and for the isocyanate it is 1.20 (10 lbs/gallon). Thematerials are typically mixed with a high dynamic shear mixer. Thecomponent temperatures should be 70-95° F. The mold temperatures shouldbe 115-135° F.

The resin material I35453R has the following description:

(a) Average molecular weight

1) Base polyether polyol=500-15,000

2) Diols=60-10,000

3) Triols=500-15,000

(b) Average functionality

1) total system=1.5-3.2

(c) Hydroxyl number

1) total systems=100-300

(d) Catalysts

1) amine=Air Products 0.1-3.0 PPH

2) tin=Witco 0.01-0.5 PPH

(e) Surfactants

1) total system=0.1-2.0 PPH

(f) Water

1) total system=0.03-3.0 PPH

(g) Pigments/dyes

1) total system=1-5% carbon black

(h) Blowing agent

1) 0.1-6.0% HFC 134A.

The I3050U isocyanate description is as follows:

(a) NCO content--22.4-23.4 wt %

(b) Viscosity, cps at 25° C.=600-800

(c) Density=1.21 g/cm³ at 25° C.

(d) Initial boiling pt.--190° C. at 5 mm Hg

(e) Vapor pressure=0.0002 Hg at 25° C.

(f) Appearance--colorless liquid

(g) Flash point (Densky-Martins closed cup)=200° C.

The materials I35453R and I3050U are available from BASF Corporation,Wyandotte, Mich. 48192.

For the arrangement shown in FIG. 8, the filter element includes sheetmetal end caps with a fluted filter paper media element potted therein.Conventional arrangements such as potted in plastisol may be used.

Dimensions of a Typical Embodiment Described in Ser. No. 08/742,244

Consider an air cleaner arrangement such as depicted in FIG. 1 used on aover the highway truck (heavy duty truck). The housing would be about13-15 inches in diameter and about 32 inches long. The element would beabout 11-13 inches in diameter and about 23-26 inches long. The I.D. ofthe smallest rib on the sealing portion of the end cap with the inlettube (prior to compression) would be about 6.78-7.44 inches. The I.D. ofthe annular surface in the housing base whereat the radial seal withsecond end cap occurs would be about 11.28-12.94 (incorrectly stated as19.94 in Ser. No. 08/742,244) inches. The O.D. of the largest step onthe second end cap, for sealing with the base, would be about 11.4-13.06inches. The bead on the base for engagement with the second end capwould be large enough to extend into the trough on the end cap about0.35 inches. The declination angle in the second end cap from its outerrim to the recess engaging the bead would be about 1.75°. Thedeclination angle on the inside of the second end cap would be about4°±2°.

Description Added to Disclosure of Ser. No. 08/742,244

It is first noted that there has been developed a preference forapplication of the techniques described in Ser. No. 08/742,244 since thetime of filing of that application. In particular, it is desirable, whenmolding end cap 24, to provide for a media stand-off to ensure that themedia 25 is supported above a remaining portion of a bottom surface ofthe mold, when the molding occurs. The mold can be provided with acircular, raised, media stand-off positioned in a portion of the moldunderneath the media 25, during molding, to provide for this. The endcap 24 would, in general, show an indent ring corresponding to the moldstand-off, at a location aligned with media 25, as a result of this.

Also, hereinbelow a preferred material for use with the embodiment ofFIGS. 9-15, as the urethane material, is provided. Such a preferredmaterial and processes for its use, may also be used with the embodimentof FIGS. 1-7, for both end caps.

It is also noted that the specific overall depiction of FIGS. 9, 10, 11,12, 13, 14 and 15 included herein, were not part of the disclosure ofSer. No. 08/742,244. Description related to them, has been added.

FIGS. 9-15 concern a variation in which the "closed" end cap having thedrainage aperture therein, while it comprises polymeric material intowhich the ends of the inner and outer supports or liners and media arepotted, further comprises a composite of polymeric material and apre-formed insert. (By "pre-formed" in this context, reference is madeto the fact that the insert was formed before a remainder of the end capwas molded.) As a result of a preferred embodiment for achieving this,shown in FIGS. 9-15, the inner surface of this end cap (which comprisesthe drainage surface to the aperture), is physically an inner surface ofthe end cap insert. This too will be understood by reference to FIGS.9-15 and the descriptions hereinbelow.

A principal difference for the embodiment of FIGS. 9-14, from theembodiment of FIGS. 1-7, concerns the referenced insert and thespecifically recited composite nature of the closed end cap having thedrainage aperture therein. There are, however, some furthermodifications in an exterior surface of the insert. These too will bedescribed in connection with FIGS. 9-15.

Attention is first directed to FIG. 9. FIG. 9 is a fragmentarycross-sectional view of an assembly according to this alternateembodiment of the present invention. Referring to FIG. 9, assembly 201comprises a combination of can 204 and element 221. In FIG. 9, referencenumeral 260 generally designates an end of can wall 261. Within end 260is positioned a cover or base 263 of can 204. Can 204, including base263, is configured analogously to can 4 and base 63 of FIG. 5, and thusincludes, analogously: a configuration which is preferably radiallysymmetric around a central axis 233; end flange 265; center 266; sealingsurface 267; bend or corner 268; end surface 269; secondary seal bead orridge 270; end recess 271; and, in center 266, a drainage aperture 218.Positioned within aperture 218, is evacuation valve 219.

Still referring to FIG. 9, filter element 221 includes end cap 224thereon. End cap 224 comprises an appropriate material, and is ofappropriate size, so that when it is pushed into and against base 263,an outer circumferential surface 275 of the end cap 224 engages surface267 of base 263 in a sealing manner. That is, an annular seal 276 isformed in region 277, circumferentially around end cap 224. As with theembodiment of FIG. 5, this is facilitated by preferably providingsurface 267 in a cylindrical configuration extending generally parallelto axis 233. As a result of the circumferential seal 276, sealingagainst flow of air is not required between any other portions of filterelement 221 and base 263. A secondary seal 280, analogous to seal 80,FIG. 5, is provided, however, between end cap 224 and base 263. Thesecondary seal 280 inhibits movement of debris or water into region 281,between element 221 and base 263.

It is noted that the particular configuration of outer circumferentialseal surface 275 of end cap 224, for the arrangement shown in FIG. 9,differs from the analogous surface 67 in the embodiment of FIG. 5. Apreferred configuration for surface 267 (and surface 67 if applied inthe embodiment of FIG. 1) is described hereinbelow in connection withthe mold FIG. 13.

Still referring to FIG. 9, end cap 224 includes a circular recess ortrough 285 therein. Trough 285, analogously to trough 85, FIG. 5, issized and configured to receive and sealingly engage bead 270. Trough285, which, in the preferred embodiment depicted has somewhat of aninverted "V" configuration (with a rounded apex) when viewed incross-section, should be sized, relative to bead 270, such that whenelement 221 is pressed against base 263, bead 270 is pushed into trough285 to form a seal therewith, capable of holding a pressure differentialat least up to about 2-4 inches of H₂ O.

Analogously to end cap 24 of the arrangement shown in FIG. 5, end cap224 comprises a soft, polymeric material. However, unlike end cap 24shown specifically in FIG. 5, end cap 224 is a composite. In particular,end cap 224 comprises: section 399 of compressible, polymeric material400; and, insert 401. Advantages which result from the provision of theinsert 401, as part of the end cap 224, will be apparent from furtherdescriptions hereinbelow.

A more detailed description of the manner of construction, to provideinsert 401, is also provided hereinbelow. In general, the insert 401 issecured to the "filter pack" which would typically comprise media 225(which is pleated paper in the preferred embodiment shown), innersupport 226, and outer support 227. Supports 226 and 227 could comprise,for example, conventional perforated metal or expanded metal medialiners. Inner liner 226 defines inner chamber 235 (which is cylindricalin the preferred embodiment shown). During assembly, after the filterpack comprising the liners 226, 227 and media 225 is prepared, insert401 would be positioned in one end of that filter pack, closing an end235a of chamber 235. The assembly comprising a filter pack and insertwould then be potted within the polymeric material which is then curedto form material 400, FIG. 9. In a typical operation, this potting wouldbe achieved by positioning the filter pack and insert 401 in anappropriate mold and distributing within the mold the uncured polymericmaterial, which is then cured. As a result of the process, againdescribed in more detail below, the insert 401 becomes permanentlyembedded within the material 400, to become secured within the filterelement 221 (between material 400 and liner 226) as a part of thecomposite end cap 224. In the final product, region 400 covers anunderside of insert 401, except in some instances for selected portionsas described below.

Attention is now directed to FIGS. 10 and 11 in which the details of thepreferred insert 401 are depicted in detail, and from which advantageswhich result from utilization of the insert 401 can be understood.Referring first to FIG. 10, which is a top plan view of the insert 401,the insert 401 has an outer perimeter 410 (circular in the preferredembodiment shown) with depending legs 411. The specific insert 401depicted in FIG. 10 includes twelve evenly radially (i.e., separatedradially by 30°) spaced legs 411, each of which terminates in a foot412. Of course, alternate numbers and specific configurations of legs411 and feet 412 may be used.

In general, insert 401 includes an upper surface 415, FIG. 10, and anopposite, bottom surface or lower surface 416, FIG. 11.

In general, upper surface 415 of insert 401 will, when element 221 isassembled, generally comprise the inner surface of composite end cap224. Thus, surface 415 will include thereon the inner drainage surfacefor directing fluid to central aperture 296 in element 224.

Referring to FIG. 11, insert 401 includes, on surface 415, an apex orupper ridge 420. Ridge 420 is preferably a perimeter ridge, and iscircular. Preferably surface 415 includes funnel section 421 therein,tapering downwardly from apex or ridge 420 to central drainage aperture422. A downward taper of 2 to 6°, typically 4°, will be preferred.Aperture 422 forms drainage aperture 296, FIG. 9, in element 221. Aswith aperture 96, FIG. 5, aperture 422 is substantially smaller ininternal dimension, i.e., diameter if round, than an internal dimension(diameter) of internal volume 235. Preferably, as with aperture 296,aperture 422 is circular, having a diameter within a range of about0.12-1 inch, typically about 0.47 inches, whereas an internal diameterof inner liner 226 is typically 6-8.5 inches, typically, 6.02, 7.78, or8.43 inches.

Referring again to FIG. 10, insert 401 includes standing ribs or ridges425. The ridges 425 are directed generally from outer perimeter 410toward aperture 422. No ridge 425, however, extends completely toaperture 422, in the preferred embodiment shown.

Also in the preferred embodiment shown, ridges 425 form pairs comprisingtwo sets of channels or troughs: troughs 428, of which there are fourdepicted in the preferred embodiment; and, troughs 429, of which thereare also four in the preferred embodiment shown. For the preferredembodiment shown, troughs 428 are identical to one another, and areseparated radially by 90°. Troughs 429 are also identical to one anotherand are separated radially by 90°. Each one of troughs 429 is evenlyspaced between two adjacent ones of troughs 428. Each of troughs 429 and428 comprises a pair of ridges 425.

Troughs 428 differ from troughs 429 in that troughs 428 are longer; thatis, troughs 428 extend a greater percentage of the distance towardaperture 422 from perimeter ridge 420. Troughs 429 are shorter (inelongated extension), primarily in order to leave open spaces 431 forliquid flow on surface 415 toward aperture 422.

Between the ridges 425 defining any given trough, 428, 429, an aperturehole through insert 401 is provided. Thus, there are two sets ofapertures: apertures 433 in troughs 428; and, apertures 434 in troughs429. Apertures 433 and 434 are generally oval-shaped, and act as freerise apertures to allow for free rise of polymeric material 400therethrough, during the molding process. This helps secure the insert401 as part of the composite end cap 224. It also facilitates acontrolled molding process, as described below. The ridges 425 helpcontain the rising polymeric material 400, during the molding process,in part to maintain substantial portions of surface 415 open, for freefluid flow thereacross.

Note that as a result of the ridges 425 being raised above surface 415,improvement in liquid flow across surface 415 is provided. This is inpart because leaf material, paper material, etc., which settles intoelement 221 may, at least in some instances, be supported above surface415 by the ridges 425.

Attention is now directed to FIG. 11. From FIG. 11, it can be understoodthat depending legs 411 generally bow outwardly from ridge 420,depending from surface 416. Preferably, each leg 411 is about 0.625inches long in extension between ridge 420 to the bottom tip of beads440, FIG. 11.

Preferably an outer radius defined by the perimeter of the legs atregions 430, is slightly larger than the inner dimension (diameter) ofliner 235; and, legs 411 are sufficiently thin to flex inwardlysomewhat, when pressed into an end of inner liner 235, during assembly.This "spring" effect can be used to temporarily secure insert 401 toliner 235 in the filter pack, during the molding operation, as describedbelow. Preferably, the outer radius of the legs at regions 430 is about0.25 inches.

Each leg 411 extends slightly outwardly from the vertical. This is tohelp facilitate manufacturing of the insert 401, so that it may be moreeasily pulled from its mold. Preferably, each leg 411 extends at anangle of about 5° from vertical.

Each leg 411 includes a tapered rib 413 extending therefrom. Each rib413 extends from just above an upper surface 441 of each foot 412 tojust below the radiussed surface 430. Ribs 413 help to temporarilysecure insert 401 to liner 235 in the filter pack, during the moldingoperation, as described below. Preferably, each rib 413 is about 60thousandths of inch thick, and extends a length of about 0.3 inches.Each rib 413 extends about 1° from vertical.

Still referring to FIG. 11, each foot 412 includes a bottom bead 440thereon. The bottom bead 440 operates as a mold stand-off, duringmolding. In particular, bottom beads 440 will support a reminder ofinsert 401 above a lower surface of a mold, during a molding operation,to help ensure that a remainder of insert 401 will be embedded withinthe resin, during the molding operation. After molding, beads 440 willeither be slightly exposed in the molded end cap, or they will becovered by a thin layer of molded material, depending upon the moldingoperation. Either condition is acceptable. Preferably, each bead 440extends at a radius of about 0.06 inches.

Each foot also includes an upper surface 441. The upper surface ispreferably at least 0.375 inches long, and, during assembly, will extendbeyond the filter pack inner liner 235 to positions underneath thefilter media 225. As a result of being positioned underneath the filtermedia 225 during assembly with a filter pack, upper surfaces 441 of thefeet 412 will operate as media stand-offs, during molding. This willprevent the media 225 from dropping all the way to the bottom of themold cavity.

Still referring to FIG. 11, attention is directed to a portion ofsurface 416 which circumscribes aperture 422. That portion or region isindicated generally at reference numeral 450. Within this region islocated a circular trench 451. (Circular when viewed in bottom planview.) The circular trench 451 preferably has a semi-circularcross-section as shown in FIG. 11, although alternative configurationscan be used. During the molding operation, trench 451 will be alignedwith, and receive, a bead in the mold. This will inhibit, duringmolding, flow of resin along the direction indicated generally by arrows452, past surface 450 and into aperture 422. The result will be aninhibition of polymeric flash at, or in, aperture 422.

As a result, it is anticipated that after a molding operation, certainportions of surface 450, indicated generally at 455 between trough 451and aperture 422, will generally be exposed, except perhaps for somesmall amount of flash from the molding operation. The exposed surface455 is viewable in FIG. 14, a bottom plan view of element 221.

Advantages to a composite end cap 224 including an insert such as thatshown in FIGS. 10 and 11, result from at least two related concerns.First, it is anticipated that insert 401 will typically be manufacturedfrom a material that can be molded, for example a molded, rigid,polystyrene or similar material. As a result of such a molding, specificconfigurations can be readily provided to surface 415 to achieveadvantageous fluid flow effects and similar effects without relying uponcontrol of conditions used to mold material 399, 400. Thus, the surfacefeatures of surface 415 are not achieved during the same operation inwhich the soft, polymeric material for the remainder of end cap 224,i.e., material 400, is formed.

In addition, the molding process to provide for polymeric material 400is facilitated. This is because a "closed mold" process is not required.Rather, free rise of the polymeric material 399 is accommodated becauseinsert 401, including apertures 433 and ridges 425, will control anddirect rise. The free rise will not effect the downward slant in regions421, to achieve a desirable drainage effect in insert 401, since theinner surface 415 of the end cap 224 is pre-formed.

In general, when the end cap 424 comprises a composite of an insert 401and polymeric material 400 as described herein, the polymeric materialmay comprise the preferred polyurethane described in application Ser.No. 08/742,244, and previously herein, molded end or similar conditions.

However, preferably the urethane comprises a material made withElastofoam I36070R resin and Elastofoam I3050U isocyanate as describedbelow. The material should be mixed as described above, except withI36070R, replacing the I35453R resin. For this material, the moldtemperature should preferably be about 105°-150° F.

The resin material I36070R has the following:

(a) Average molecular weight

1) Base polyether polyol=500-15,000

2) Diols=60-10,000

3) Triols=500-15,000

(b) Average functionality

1) total system=1.5-3.2

(c) Hydroxyl number

1) total systems=100-300

(d) Catalysts

1) amine=Air Products 0.1-3.0 PPH

(e) Surfactants

1) total system=0.1-2.0 PPH

(f) Water

1) total system=0.03-3.0 PPH

(g) Pigments/dyes

1) total system=1-5% carbon black

The Elastofoam I3050U isocyanate description is as follows:

(a) NCO content--22.4-23.4 wt. %

(b) Viscosity, cps at 25° C.=600-800

(c) Density=1.21 g/cm³ at 25° C.

(d) Initial boiling pt.--190° C. at 5 mm Hg

(e) Vapor pressure=0.0002 Hg at 25° C.

(f) Appearance--colorless liquid

(g) Flash point (Densky-Martins closed cup)=200° C.

The materials Elastofoam I36070R and Elastofoam I3050U are availablefrom BASF Corporation, Wyandotte, Mich. 48192.

Preferably the insert comprises a rigid material, such as moldedpolystyrene. Of course, a variety of specific configurations andalternatives to the arrangement shown in FIGS. 10 and 11 can be used.However, preferred configurations and dimensions are provided herein.

With respect to the liner material, no particular preference is made. Ingeneral, it is foreseen that the liner will comprise either perforatedmetal or expanded metal, for example G60 galvanized steel, having athickness of about 0.03 inches. Such liners are commonly used in othertypes of large filter elements for trucks, for example.

As to the filter material, with respect to the principles of the presentinvention, no particular preference exists. The principles of thepresent invention can be applied with any of a wide variety ofmaterials. For example, pleated paper or cellulose materials, such asconventionally used in truck filters, may be used. Synthetic materials,or cellulose materials, having synthetic (polymeric or glass) fibersapplied thereto, may also be used. Expanded polytetrafluoroethylenelayers, applied on a surface, or in composites, may be used. Inaddition, nonwoven fibrous constructions, or composites of nonwovenfibrous media and pleated media, may also be used. Indeed, arrangementsnot existing and yet to be developed can be accommodated, by compositeend caps made according to the processes described herein. This will beapparent, from a more detailed description of the method of assembly.

In FIG. 12, a schematic representation of a preferred process formanufacturing a filter element according to the composite of FIGS. 9, 10and 11 is provided.

Referring to FIG. 12, a filter pack is indicated generally at 500. Thefilter pack comprises outer liner 227, media 225, and inner liner 226.The filter pack 500 is shown aligned to receive insert 401 therein, withfeet 411 positioned under media 225, and with a remainder of insert 401positioned within inner chamber 235. The combination of filter pack 500and insert 401 would then be positioned within mold 501. The appropriateresin mix would be positioned in the mold as well, and cured. Again,free rise conditions for curing are allowable, due in part to the designof insert 401.

Attention is directed to FIG. 13, which indicates a schematiccross-section of a usable mold 501. Note the mold includes bead 502 forengagement with trough 451 in insert 401, FIG. 11, discussed above.Center post 503 fits through aperture 422 in insert 401, and ensures aproper positioning as well as inhibition of flash within the aperture422. Note the positioning of bead 504, which will generate trough 285,FIG. 9. Also note the positioning of stand-off 505, which is formed as aring in mold 501. Stand-off 505 will receive beads 440 positionedthereon, during molding. This is illustrated in FIG. 15, schematically,in which insert 401 is shown positioned within mold 501.

Some Preferred Dimensions for Arrangements According to FIGS. 9-15

Consider an air cleaner arrangement such as depicted in FIG. 1 used on aover the highway truck (heavy duty truck). The housing would be about11-15 inches in diameter and about 32 inches long. The element would beabout 9-13 inches in diameter and about 22-26 inches long. The I.D. ofthe smallest rib on the sealing portion of the end cap with the inlettube (prior to compression) would be about 5.15 inches. The I.D. of theannular surface in the housing base whereat the radial seal with secondend cap occurs would be about 9.52 inches. The O.D. of the largest stepon the second end cap, for sealing with the base, would be about 9.64inches. The bead on the base for engagement with the second end capwould be large enough to extend into the trough on the end cap about0.35 inches. The declination angle in the second end cap from its outerrim to the recess engaging the bead would be about 1.75°. Thedeclination angle on the inside of the second end cap would be about4°±2°.

The standing ribs or ridges 425 on the insert would have a height ofabout 0.077 inches, and a thickness at a distal end (free end) of about0.042 inches. Each of the ridges 425 between the base proximate to theregions 421 and the free end would be curved on a radius of about 0.062inches. The distance between a pair of free ends of two of the ridgeswould be about 0.4 inches. Apertures 433 and 434 would have radii ateach respective end of about 0.125 inches.

Circular trench 451 would have a semi-circular cross-section. The radiusof the cross-section would be about 0.031 inches. The diameter ofcircular trench 451 would be about 0.736 inches.

The diameter for the insert extending from the outermost end tip of oneof the feet to the outermost end tip of a diametrically opposite footwould be about 9.265 inches. The diameter of the insert extending fromthe outermost part of one of the legs (not including the foot) to theoutermost part of a diametrically opposite leg (not including the foot)would be about 8.515 inches. The inner radius of each leg 411 as itbends from a top surface of the insert down toward its foot would beabout 0.187 inches. The outer radius of each leg 411 as it bends from atop surface of the insert down toward its foot would be about 0.25inches. The radius of each leg 411 as it bends from its substantiallyvertically extension to its foot would be about 0.03 inches. The radiusof each bead 440 would be about 0.06 inches. The angle of declination atramp section 453 would be about 30° from horizontal, and on a radius ofabout 0.125 inches.

Each rib 413 on legs 411 would be about 60 thousandths of inch thick,and extend a length of about 0.3 inches. Each rib 413 would extend about1° from vertical. Each leg 411 would extend at an angle of about 5° fromvertical, and be about 0.625 inches long in extension between ridge 420to the bottom tip of beads 440. The upper surface of each foot would beabout 0.375 inches long.

What is claimed is:
 1. An air filter element comprising:(a) first andsecond, opposite, end caps; (b) filter media; (c) an inner linerdefining an open filter interior; (d) said first end cap having an airinlet opening therein; (e) said second end cap having:(i) a centraldrainage aperture extending therethrough; and, (ii) an interior surfaceconstructed and arranged to direct moisture on said second end capinterior surface to said central drainage aperture.
 2. An air filterelement according to claim 1 wherein:(a) said second end cap comprises acomposite including:(i) an inner insert having a first, inner, surfacedefining said second cap interior surface and an opposite, second,outer, surface; said inner insert having a central aperture extendingtherethrough; and, (ii) a compressible polymeric material covering atleast a portion of said outer surface of said insert; said inner linerbeing embedded in said compressible polymeric material; said polymericmaterial having a central aperture therein aligned with said aperture insaid inner insert, to form said central drainage aperture.
 3. A filterelement according to claim 2 wherein:(a) said compressible polymericmaterial comprises a material having an as molded density within therange of 14-22 pounds per cubic foot.
 4. A filter element according toclaim 3 wherein:(a) said compressible polymeric material comprisespolyurethane foam.
 5. A filter element according to claim 2 wherein:(a)said inner insert includes a circular trough in said outer surfacepositioned to extend around said insert central aperture.
 6. A filterelement according to claim 5 wherein:(a) said insert trough issemi-circular in cross-section.
 7. A filter element according to claim 2wherein:(a) said inner insert includes a plurality of free riseapertures therein; and, (b) a portion of said compressible polymericmaterial projects through said free rise apertures.
 8. A filter elementaccording to claim 7 wherein:(a) each of said free rise apertures ispositioned between an associated pair of ridges extending outwardly fromsaid insert first surface.
 9. A filter element according to claim 8wherein:(a) each pair of ridges comprises first and second, spaced,walls extending along a direction from an outer perimeter of said innerinsert toward said central drainage aperture.
 10. A filter elementaccording to claim 7 wherein:(a) said inner insert includes a pluralityof pairs of wall projections comprising a first set of pairs and asecond set of pairs;(i) each pair of said second set of pairs beingshorter, in longitudinal extension toward said central drainageaperture, than each pair of said first set of pairs.
 11. A filterelement according to claim 10 wherein:(a) each pair of said first set ofpairs is spaced from each adjacent pair of said first set by a member ofsaid second set of pairs; and, (b) each pair of said second set of pairsis spaced from each adjacent pair of said second set by a member of saidfirst set of pairs.
 12. A filter element according to claim 11wherein:(a) said first set of pairs consists of four pairs of walls; (b)said second set of pairs consists of four pairs of walls; and, (c) eachpair of walls is evenly, radially, spaced on said inner insert firstsurface and around said central drainage aperture.
 13. A filter elementaccording to claim 12 wherein:(a) said inner insert has an outerperiphery with a plurality of spaced legs extending outwardlytherefrom:(i) said spaced legs projecting axially outwardly from saidinner insert in a direction from said inner insert second side.
 14. Afilter element according to claim 13 wherein:(a) each one of said spacedlegs has a radially directed foot thereon; each radially directed footextending away from an associated leg by a distance of at least 0.375inches.